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Diffstat (limited to 'net/ipv4/tcp_cong.c')
-rw-r--r--net/ipv4/tcp_cong.c97
1 files changed, 81 insertions, 16 deletions
diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 38f2f8aa4ceb..63c29dba68a8 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -13,6 +13,7 @@
#include <linux/types.h>
#include <linux/list.h>
#include <linux/gfp.h>
+#include <linux/jhash.h>
#include <net/tcp.h>
static DEFINE_SPINLOCK(tcp_cong_list_lock);
@@ -31,6 +32,34 @@ static struct tcp_congestion_ops *tcp_ca_find(const char *name)
return NULL;
}
+/* Must be called with rcu lock held */
+static const struct tcp_congestion_ops *__tcp_ca_find_autoload(const char *name)
+{
+ const struct tcp_congestion_ops *ca = tcp_ca_find(name);
+#ifdef CONFIG_MODULES
+ if (!ca && capable(CAP_NET_ADMIN)) {
+ rcu_read_unlock();
+ request_module("tcp_%s", name);
+ rcu_read_lock();
+ ca = tcp_ca_find(name);
+ }
+#endif
+ return ca;
+}
+
+/* Simple linear search, not much in here. */
+struct tcp_congestion_ops *tcp_ca_find_key(u32 key)
+{
+ struct tcp_congestion_ops *e;
+
+ list_for_each_entry_rcu(e, &tcp_cong_list, list) {
+ if (e->key == key)
+ return e;
+ }
+
+ return NULL;
+}
+
/*
* Attach new congestion control algorithm to the list
* of available options.
@@ -45,9 +74,12 @@ int tcp_register_congestion_control(struct tcp_congestion_ops *ca)
return -EINVAL;
}
+ ca->key = jhash(ca->name, sizeof(ca->name), strlen(ca->name));
+
spin_lock(&tcp_cong_list_lock);
- if (tcp_ca_find(ca->name)) {
- pr_notice("%s already registered\n", ca->name);
+ if (ca->key == TCP_CA_UNSPEC || tcp_ca_find_key(ca->key)) {
+ pr_notice("%s already registered or non-unique key\n",
+ ca->name);
ret = -EEXIST;
} else {
list_add_tail_rcu(&ca->list, &tcp_cong_list);
@@ -70,9 +102,50 @@ void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca)
spin_lock(&tcp_cong_list_lock);
list_del_rcu(&ca->list);
spin_unlock(&tcp_cong_list_lock);
+
+ /* Wait for outstanding readers to complete before the
+ * module gets removed entirely.
+ *
+ * A try_module_get() should fail by now as our module is
+ * in "going" state since no refs are held anymore and
+ * module_exit() handler being called.
+ */
+ synchronize_rcu();
}
EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control);
+u32 tcp_ca_get_key_by_name(const char *name)
+{
+ const struct tcp_congestion_ops *ca;
+ u32 key;
+
+ might_sleep();
+
+ rcu_read_lock();
+ ca = __tcp_ca_find_autoload(name);
+ key = ca ? ca->key : TCP_CA_UNSPEC;
+ rcu_read_unlock();
+
+ return key;
+}
+EXPORT_SYMBOL_GPL(tcp_ca_get_key_by_name);
+
+char *tcp_ca_get_name_by_key(u32 key, char *buffer)
+{
+ const struct tcp_congestion_ops *ca;
+ char *ret = NULL;
+
+ rcu_read_lock();
+ ca = tcp_ca_find_key(key);
+ if (ca)
+ ret = strncpy(buffer, ca->name,
+ TCP_CA_NAME_MAX);
+ rcu_read_unlock();
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tcp_ca_get_name_by_key);
+
/* Assign choice of congestion control. */
void tcp_assign_congestion_control(struct sock *sk)
{
@@ -253,25 +326,17 @@ out:
int tcp_set_congestion_control(struct sock *sk, const char *name)
{
struct inet_connection_sock *icsk = inet_csk(sk);
- struct tcp_congestion_ops *ca;
+ const struct tcp_congestion_ops *ca;
int err = 0;
- rcu_read_lock();
- ca = tcp_ca_find(name);
+ if (icsk->icsk_ca_dst_locked)
+ return -EPERM;
- /* no change asking for existing value */
+ rcu_read_lock();
+ ca = __tcp_ca_find_autoload(name);
+ /* No change asking for existing value */
if (ca == icsk->icsk_ca_ops)
goto out;
-
-#ifdef CONFIG_MODULES
- /* not found attempt to autoload module */
- if (!ca && capable(CAP_NET_ADMIN)) {
- rcu_read_unlock();
- request_module("tcp_%s", name);
- rcu_read_lock();
- ca = tcp_ca_find(name);
- }
-#endif
if (!ca)
err = -ENOENT;
else if (!((ca->flags & TCP_CONG_NON_RESTRICTED) ||